Sharif Digital Repository

We report the results of the electronic structure calculation of a newly discovered member of the YBCO high-T c family, i.e., Y 3Ba 5Cu 8O 18 (Y358) with T c>100, based on the full-potential linearized augmented plane waves method (FP-LAPW) of density functional theory in the generalized gradient approximation (GGA). The evolution of the number of hole carriers in different sites of the CuO 2 planes and CuO chains has been investigated in comparison with the other YBCO family members, i.e., Y123, Pr123, Y124, and Y247. The results suggest that pumping hole carriers out of the chains toward the planes enhances the transition temperature. The band structure calculations have been performed for... 

The electronic structures of PrBa2Cu3O7 (Pr123), Pr2Ba4Cu7O15-y (Pr247), and PrBa2Cu4O8 (Pr124) cuprates have been obtained using density-functional theory in the local spin density approximation plus onsite Coulomb interaction (LSDA + U). Onsite Hubbard correlation, U, has been considered for Pr-f and Cu-d orbitals and the effects of considering these correlation corrections on the Pr-O hybridizations have been inspected. Results imply that the Pr ionization state in Pr123 system is constituted from two different configurations, and the energy of the f states in these two configurations has an important role in superconductivity properties of the system. Our calculations also show that in... 

The interaction between fault tolerance and energy consumption is an interesting avenue in the realm of designing embedded systems. In this paper, a scheme for reducing energy consumption in conventional standby-sparing systems is introduced. In the proposed method, the primary unit exploits dynamic voltage scaling (DVS) and dynamic power management (DPM) is employed for the spare unit. The framework which is used in the primary unit is composed of a feedback system to follow up workload along with a three-layer yet light-weight energy manager which guarantees hard real-time constraints of the system. Moreover, an optimal approach (but not practical) as a margin for the minimum energy... 

We present linear-response density-functional theory calculations for the high-Tc superconductor La2-xBaxCuO4 to study the doping dependence of phonon dispersion. Using the virtual crystal approximation, the doping range up to x = 0.20 is investigated. We find unstable phonon modes that soften around high-symmetry points of the Brillouin zone. These branches are analyzed as a function of doping and pressure. The structural distortions related to these phonons are in accordance with the observed phase transitions from the high-temperature tetragonal (HTT) phase to the low-temperature orthorhombic (LTO) and the low-temperature tetragonal... 

Ab initio frozen-phonon calculations have been performed for k = 0 A g Raman modes of superconducting GdBa2Cu3O 7 and insulating PrBa2Cu3O7. We have used the generalized gradient approximation full-potential linear augmented plane-wave method in our calculations by Wien2k code. Results have been compared with other computational and experimental data for similar systems. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA  

The facility placement in supply chain management entails suppliers and consumers along with the terminals in between for distributing commodities. This study seeks to find the best terminal placement by taking into consideration the costs for both transportation and terminal construction. We call this a supplier-terminal-consumer (STC) problem and show that the STC is an NP-hard quadratic assignment problem. The NP-hard problems in real-size are proven to be intractable; hence, we develop a two-fold heuristic method for solving the STC problems. First, we identify the commodity flow by using a logit-based mathematical programming (Logit-MP) methodology based on the demand for the commodity... 

Energy reduction in embedded processors is a must since most embedded systems run on batteries and processor energy reduction helps increase usage time before needing a recharge. Register files are among the most power consuming parts of a processor core. Register file power consumption mainly depends on its size (height as well as width), especially in newer technologies where leakage power is increasing. We provide a register file architecture that, depending on the application behavior, dynamically (i) adapts the width of individual registers, and (ii) puts partitions of temporarily unused registers into low-power mode, so as to save both static and dynamic power. We show that our scheme... 

In this study, the robustness of the Travelling Salesman Problem (TSP) routes is investigated by recognising the special combinatorial structures of Kalmanson matrices. A recognition algorithm encompassing three procedures based on combinatorial and linear programming (LP) is developed and executed on several randomly generated instances. These procedures produce three lower bounds which provide guarantees on the optimality of the solutions. Computational experiments show that the proposed LP-based procedure performs efficiently well across all problem dimensions and provides the best lower bounds to the TSP. This is supported by an average deviation of less than 7% between the TSP tour... 

Adding a new road to help traffic flow in a congested urban network may at first appear to be a good idea. The Braess Paradox (BP) says, adding new capacity may actually worsen traffic flow. BP does not only call for extra vigilance in expanding a network, it also highlights a question: Does BP exist in existing networks? Literature reveals that BP is rife in real world. This study proposes a methodology to find a set of roads in a real network, whose closure improve traffic flow. It is called the Braess Paradox Detection (BPD) problem. Literature proves that the BPD problem is highly intractable especially in real networks and no efficient method has been introduced. We developed a... 

This article presents a multi-standard transmitter based on the eight-path architecture with a fully digital baseband (BB) input, covering the frequency band from 300 MHz to 1.5 GHz, while all harmonics and the distortion product of C-IMD3 are rejected to better than -40 dBc. The proposed architecture is based on the multipath technique in which the amplitude weighting algorithm is implemented in the digital domain. The fully digital input baseband section of the architecture eliminates the need for power-consuming circuit modules, such as mixers, high-frequency filters, and amplifiers, thus simplifying the required circuitry and improving the overall performance in terms of the operating... 

Checkpointing with rollback recovery is a well-established technique to tolerate transient faults. However, it incurs significant time and energy overheads, which go wasted in fault-free execution states and may not even be feasible in hard real-time systems. This paper presents a low-overhead two-state checkpointing (TsCp) scheme for fault-tolerant hard real-time systems. It differentiates between the fault-free and faulty execution states and leverages two types of checkpoint intervals for these two different states. The first type is nonuniform intervals that are used while no fault has occurred. These intervals are determined based on postponing checkpoint insertions in fault-free... 

This study presents a seasonal multi-product multi-period inventory control model with inventory costs obtained under inflation and all-unit discount policy. The products are delivered in boxes of known quantities and both backorder and lost-sale quantities are considered in case of shortage. The goal is to find a representative set of Pareto optimal solutions (including the ordering quantities) in different periods and to minimize both the total inventory cost (i.e. ordering, holding, shortage, and purchasing costs) and the total storage space, simultaneously. Three multi-objective optimization algorithms of non-dominated sorting genetic algorithm (NSGA-II), non-dominated ranked genetic... 

Due to the tight power envelope, in the future technology nodes it is envisaged that not all cores in a many-core chip can be simultaneously powered-on (at full performance level). The power-gated cores are referred to as Dark Silicon. At the same time, growing reliability issues due to process variations and soft errors challenge the cost-effective deployment of future technology nodes. This paper presents a reliability management system for Dark Silicon chips (dsReliM) that optimizes for reliability of on-chip systems while jointly accounting for soft errors, process variations and the thermal design power (TDP) constraint. Towards the TDP-constrained reliability optimization, dsReliM... 

Many cities are struggling to keep pace with limited budgets and rapid growth. Economic development models involving public-private partnerships (P3s) can help drive economic revitalization. The choice of partners plays a vital role in the success or failure of sustainable P3 initiatives. In this study, we propose a novel integrated sustainable private partner selection framework in P3s. The proposed model is composed of the best-worst method (BWM), the weighted influence non-linear gauge system (WINGS), and the technique of order preference similarity to the ideal solution (TOPSIS). The BWM is used to identify the importance weights of the economic, environmental, social, and technological... 

The tourism and hospitality industry significantly impacts socio-economic development and cultural growth in developing countries. This study develops an integrated multicriteria decision-making and optimization model for partner selection in public-private partnership (PPP) projects in the hospitality industry. The proposed model uses a weighted influence non-linear gauge system to evaluate the partners. A multi-objective optimization model is then utilized to select a partner for each PPP project using a linear programming metric solution approach. A case study demonstrates the applicability of the proposed model in a PPP project in Iran to renovate and convert historic houses into hotels... 

Many companies face challenges in reducing their supply chain costs while increasing sustainability and customer service levels. A comprehensive framework for a sustainable closed-loop supply chain (CLSC) network is a practical solution to these challenges. Hence, for the first time, this study considers an integrated multi-objective mixed-integer linear programming (MOMILP) model to design sustainable CLSC networks with cross-docking, location-inventory-routing, time window, supplier selection, order allocation, transportation modes with simultaneous pickup, and delivery under uncertainty. An intelligent simulation algorithm is proposed to produce CLSC network data with probabilistic... 

To mitigate the environmental issues related to the utilisation of ordinary portland cement (OPC) in concrete mixtures, attempts have been carried out to find alternative binders such as rice husk ash (RHA) as replacements for OPC. This study contributes to moving from the traditional laboratory-based methods for the determination of compressive strength (CS) towards machine learning-based approaches by developing three accurate models (i.e. artificial neural network (ANN), multivariate adaptive regression spline (MARS) and M5P model tree) for the estimation of the CS of concretes containing RHA. For this purpose, the models were developed employing 909 data records collected through...